This invention relates to an improved pivotal connection between the narrow slats which form an accordion-type folding shutter which substantially increases the resistance to slat separation caused by impacts against the shutter.
Conventional accordion-type folding shutters generally comprise numerous, vertically arranged, narrow slats which are pivotly connected together along their adjacent edges. The shutters may be extended or unfolded to overlay or cover an opening formed in a building, such as a window or door opening. Alternatively, the shutter may be folded so that its slats are compressed together to clear the opening. Normally, the shutters are extended for the purpose of protecting against intrusion or penetration through the building opening. Therefore, the shutters must be made in such a manner as to resist the forces that are applied by the impact of wind-hurled objects or manually applied objects.
Since conventional shutters are typically connected together by tube-like connector formations formed on the opposite edges of the respective slats, with one formation or member being sized to fit within and to pivot within the adjacent member, substantial impact forces can break apart or separate adjacent slats at their connections. Thus, conventional shutters are vulnerable to penetration or slat separation due to relatively strongly applied impacts against the pivotal connections between their adjacent slats.
Examples of such types of accordion folding shutters and of the connections between their adjacent slats are disclosed in U.S. Pat. No. 3,670,797 issued Jun. 20, 1972 to Sassano (e.g., see FIGS. 4 and 5 of the drawings) and U.S. Pat. No. 5,097,883 issued Mar. 24, 1992 to Robinson et al. (e.g., see FIGS. 8, 10 and 11).
In U.S. Pat. No. 3,670,797, an inner, tubular-like pivot member (e.g., see, FIG. 5) having a substantially greater wall thickness than the remainder of the slat, fits within an outer pivot member. The outer tubular-like member is provided with inwardly extending edge beads along the edges which define a slot through which a bent edge of the slat is fitted for integral connection with the inner tube-like member. Although, those beads assist in spacing the outer surface of the inner member from the inner surface of the outer member, they tend to axially mis-align the inner and outer members, particularly during folding and unfolding of the shutters.
The pivotal connection system disclosed in U.S. Pat. No. 5,097,883, includes an inner tube-like member on one slat fitted within an outer tube-like member on the next slat. The inner member is connected, through a short, angularly bent-edge portion, to its respective slat. Each of the inner and outer members is provided with an elongated slot. The edges of the outer member slots have inwardly extending beads. The edge of the inner member slots have outwardly extending beads (e.g., see FIGS. 10 and 11). However, those bead constructions limit the angle between adjacent slats to approximately 60 degrees when the shutter is extended. Hence, a considerable number of slats are required to cover a given lineal distance. That construction, also, tends to require relatively wide and thick slats and have a limited resistance to separation of the slat connections under impact.
The present invention relates to an improved pivotal connection which substantially increases the separation and penetration resistance of the slat connections and permits the use of thinner, relatively narrower slats which extend apart at a considerable angle as compared with the abovedescribed shutters.